Athetoid cerebral palsy is caused by damage to the cerebellum and basal ganglia of the brain; which control coordination and posture. The damage usually occurs before the cerebellum has had the chance to develop fully. This can be the result of cerebral hypoxia; when infections or injuries interfere with oxygen’s ability to reach the cells in the brain.
Athetoid cerebral palsy is sometimes referred to as dyskinetic cerebral palsy, or ADCP. ADCP causes both hypertonia and hyptonia in the muscles, and people with the condition have no ability to control their muscle tone. Muscles may alternate between being overly tense to floppy, causing the involuntary movements associated with the condition. This mixed muscle tone causes movements that are typically slow and uncoordinated, though small, random and repetitive uncontrolled movements may also be present. People with athetoid cerebral palsy often find their symptoms become more prominent when they are under emotional stress or excited, and symptoms usually lessen while they are asleep.
As with other forms of cerebral palsy, ADCP in non-progressive and the damage to the cerebellum and basal ganglia does not worsen with time. However, the inability to control muscle tone can cause the muscles to become weaker with time, leading to an increase in symptoms as a person ages. Athetoid cerebral palsy is non-contagious, as it is not caused by a bacteria or virus and cannot be transmitted to other people.
Children with ADCP often have difficulty meeting major motor skills milestones, such as sitting up on their own, crawling, standing and walking. Speech problems are incredibly common in both adults and children, as are difficulties chewing and swallowing. Speech, physical and occupational therapy can help people with athetoid cerebral palsy improve their speaking skills, posture, mobility and quality of life. Between 30% and 78% of people with athetoid cerebral palsy have normal intelligence, and up to 50% have some degree of mobility and ambulation.
The severity of symptoms and long-term prognosis is dependent on how damaged the cerebellum and basal ganglia are and how deep the lesions in the brain run. Athetoid cerebral palsy may be classified as:
• Mild (minimal symptoms, ability to function)
• Moderate (increased symptoms that make functioning difficult)
• Severe (extreme symptoms and little ability to perform everyday tasks)